1. Technical Field of the Invention
The present invention relates to card-based transaction systems. More particularly, and not by way of any limitation, the present invention relates to volatile-memory based cards and storage receptacles therefor.
2. Description of Related Art
The use of information bearing cards having electronic circuitry thereon (also known as "Smart Cards") has been proliferating in a variety of fields, for example, financial services, point-of-sale transaction applications, prepaid phone/information access services, toll collection applications, health care services, et cetera. To promote uniformity and cross-platform compatibility, standards have emerged in the industry regarding various aspects of the cards such as, for example, physical characteristics, communication protocols and so forth.
Advances in Very Large Scale Integration (VLSI) techniques of integrated circuit (IC) design and semiconductor manufacturing have made it possible to incorporate additional functionality in the microchips or ICs that are embedded in the card substrates. Further, because of the increased use of highly sensitive information in these cards, the need for information security has dramatically increased.
Existing smart cards typically provide information security by utilizing known cryptographic methods and algorithms. The encryption and decryption key variables and other sensitive information inputs used in these methods are typically provided in Electrically Erasable and Programmable Read-Only Memory (EEPROM) storage on the card. Dedicated processors or cryptographic engines are also provided on the card sometimes to optimize computational load.
Current smart card solutions, with or without information security, have several deficiencies and shortcomings. For example, existing smart cards may fail when, due to applied mechanical stress, the rigid semiconductor die or chip of the card breaks. It can be readily appreciated that mechanical stress is inherent in most typical smart card storage environments, i.e., cardholder's personal effects such as wallets, pockets, purses, et cetera.
Where information security is provided based on nonvolatile storage, there is a possibility that the card's IC may be microprobed by unauthorized persons to determine the charge state of individual memory cells and thereby gather sensitive information stored therein. Clearly, such a possibility, however remote, cannot be tolerated in numerous applications. Yet another detrimental possibility exists where a transaction is conducted by the legitimate cardholder but under a threat from an unauthorized person.
Accordingly, it should be readily appreciated by those skilled in the art that although there exist several single chip secure cards today, no one card system addresses these and other deficiencies and shortcomings by providing all of the innovative and advantageous features of the present invention described and claimed hereinbelow.